Which of the following is NOT correct about elements?

(10 Points)

A. Elements cannot be broken down into simpler substances.

B. Elements are represented by chemical formulas.

C. Elements are pure substances.

D.Elements can combine chemically to form compounds.

B. Elements are represented by chemical formulas.

Elements are pure substances, which means that they cannot be broken down into simpler substances. The element is the most basic substance that exists, breaking it down further means breaking it down into protons, neutrons, and electrons, which is no longer a substance.

Elements have chemical properties that allow them to form different types of bonds with other elements.

However, elements *alone* are not represented by their chemical formulas. Only chemical bonds or ions are represented by a chemical formula.

a. 34 mL; b. 110 mL

a. A tablet containing 150 Mg(OH)₂

Mg(OH)₂ + 2HCl ⟶ MgCl₂ + 2H₂O

Moles of Mg(OH)₂ = 150 mg Mg(OH)₂ × [1 mmol Mg(OH)₂/58.32 mg Mg(OH)₂

= 2.572 mmol Mg(OH)₂

Moles of HCl = 2.572 mmol Mg(OH)₂ × [2 mmol HCl/1 mmol Mg(OH)₂]

= 5.144 mmol HCl

Volume of HCl = 5.144 mmol HCl × (1 mmol HCl/0.15 mmol HCl) = 34 mL HCl

b. A tablet containing 850 mg CaCO₃

CaCO₃ + 2HCl ⟶ CaCl₂ + CO₂ + H₂O

Moles of CaCO₃ = 850 mg CaCO₃ × [1 mmol CaCO₃/100.09 mg CaCO₃

= 8.492 mmol CaCO₃

Moles of HCl = 8.492 mmol CaCO₃ × [2 mmol HCl/1 mmol CaCO₃]

= 16.98 mmol HCl

Volume of HCl = 16.98 mmol HCl × (1 mL HCl/0.15 mmol HCl) = 110 mL HCl